This Quantitative Pharmacology Assay (QPA) Core (C) supports the program entitled "Developmental and Translational Pharmacology of Pediatric Antimicrobial Therapy", submitted as an application responsive to RFA-HD-10-026: Specialized Center in Research in Pediatric Developmental Pharmacology (RPDP) Program (U54). The overall theme of the proposed program at UC San Diego is to bring together non-clinical and clinical experts in the fields of developmental physiology, pharmacology, and infectious diseases and conduct translational research to advance the field of pediatric developmental pharmacology. The QPA Core will provide timely, accurate and cost effective quantitative assays in support of the UC San Diego Research in Pediatric Development Pharmacology (RPDP) Center Projects and Pilot Projects. It will adopt published analytical methods and develop de-novo approaches to measure drugs, their metabolites and as antimicrobial peptides using small sample volumes appropriate for pediatric populations. These assay will cover various matrices including, plasma, intracellular, urine and tissue. Various methodologies are available including HPLC with UV detection, RIA, LC/MS/MS, and GC/MS. The QPA Core maintains medical licensure under CLIA and participates in NIAID's Clinical Pharmacology Quality Assurance program. The laboratory will work closely with the PM Core to determine assay sensitivity requirements so the most cost effective method can be used. The QPA Core will also collaborate with the Training &Outreach Core to provide assay methodology training opportunities for students, residents and fellows.